A French soldier in the Central African Republic with a patch bearing a motto used by the Nazi Waffen-SS. Photograph: Fred Dufour/AFP/Getty Images

French military chiefs have launched an investigation to after a soldier serving in the Central African Republic was pictured wearing a Nazi slogan on his uniform.

The man, reportedly from an elite parachute regiment, was photographed in fatigues carrying his rifle. On the right sleeve of his uniform was sewn a round patch carrying the number 32 on a French flag and the words “Meine Ehre heisst Treue” (“my honour is loyalty”). The motto was used by Nazi Waffen-SS soldiers during the second world war and is banned in a number of countries including Germany and Austria.

Embarrassingly, the photograph was part of a series posted on the French army’s official external operations Facebook page before it was taken down.

“The insignia is not official and he will be sanctioned, but we should make this an affair of state and certainly this tiny incident should not stain the very difficult mission the 8th Marine Infantry Parachute Regiment are carrying out in an exemplary manner in the CAR.”

France has sent about 1,600 troops to the Central African Republic to disarm rebels from rival Christian and Muslim militias who have reportedly massacred more than 1,000 civilians and threaten to drag the country into civil war.

“This is an unacceptable attitude that doesn’t reflect the reality of the armed forces,” army spokesman Colonel Gilles Jaron said.

“The soldier will be immediately suspended as soon as we have identified him,” he added and confirmed that the patch is not part of the army’s uniform.

The controversy follows a similar row in November, when a French soldier in Mali was photographed wearing a scarf printed with a death mask. In 2008, three French soldiers from another parachute regiment, also based in south-west France, were photographed making a Hitler salute while wrapped in a Nazi flag bearing a swastika.